1. Field of the Invention
This invention relates to a gap adjusting device which is disposed in a recording apparatus being provided with a recording head which performs recording on a recording medium, a platen which is disposed in opposition to the recording head and defines a gap between a head surface of the recording head and the recording medium, a carriage on which the recording head is mounted and which reciprocates in a main scanning direction, and a pair of carriage guide shafts which guide a reciprocating motion of the carriage, and a recording apparatus which was provided with the adjusting device.
Further, the invention relates to a liquid ejection apparatus such as an ink jet recording apparatus, which discharges (ejects) liquid such as ink from its head and performs recording on a recording medium (a medium to which liquid is ejected), and a gap adjusting device which is disposed in the liquid ejection apparatus.
Here, the liquid ejection apparatus is used as a meaning which is not apply only to a recording apparatus such as a printer, a copying machine and a facsimile, which uses an ink jet recording head and which discharges ink from the recording head to perform recording on a recording medium, but also to an apparatus which ejects liquid instead of ink, which corresponds to its application, to a medium to which liquid is ejected, which corresponds to the recording medium, from a liquid ejection head which corresponds to the recording head, to have the liquid attached to the medium to which liquid is ejected.
As liquid ejection heads other than the recording head, it is possible to mention a color material ejecting head which is used in manufacturing color filters such as liquid displays, an electrode material (electric conductive paint) ejecting head which is used in forming electrodes of an organic EL display and a surface light ejecting display (FED) etc., a living organic material ejecting head which is used in manufacturing bio-chips, a sample ejecting head as a precision pipet, and so on.
2. Description of the Related Art
Hereinafter, as one example of the ink jet recording apparatus or the liquid ejection apparatus, an ink jet printer is picked up and will be described. There exists an ink jet printer of such a configuration that a carriage, on which a recording head is mounted, is supported by a pair of carriage guide shafts which were disposed on a front surface side and a rear surface side of the carriage. In the ink jet printer of such the configuration, disposed is a paper gap adjusting device, which can automatically adjust a paper gap in accordance with a thickness of a recording medium, in order to correspond to papers with various thicknesses and a CD-R tray etc.
The paper gap defines a distance between a head surface of a recording head and a paper, and becomes an extremely important factor in performing recording of high precision. As a paper gap adjusting device, adopted is such a configuration that a height of a head surface of a recording head, which is mounted on a carriage, becomes variable by lifting and lowering the carriage by a predetermined stroke, to a platen which is disposed in a fixed state. Then, in order to lift and lower a pair of carriage guide shafts at identical timing, with an identical stroke, in synchronization, a paper gap adjusting device, which is of the following configuration, is adopted.
Firstly, there exists a paper gap adjusting device which was configured such that a driving force is supplied from a drive motor for paper feed, and motive power is transmitted through a rack and pinion mechanism and a link mechanism to a pair of carriage guide shafts. However, in a paper gap adjusting device with such the configuration, it becomes such a complex configuration that a rotary motion of the drive motor is converted into a linear motion, and further, converted again into a rotary motion through the link mechanism, and therefore, the number of components becomes large, and the apparatus grew in size. Particularly, in the rack and pinion mechanism and the link mechanism, an operation area of a linear motion portion becomes large-by any mechanisms, and therefore, it makes it difficult to design a layout for securing the operation area.
Secondly, as shown in Japanese Patent Publication No. JP-A-2002-67428, there exists a paper gap adjusting device, which was configured such that a carriage guide shaft is made as an eccentric shaft configuration, and thereby, it moves up and down along with rotation of the carriage guide shaft. However, in a paper gap adjusting device with such the configuration, in order to enlarge a changing amount of the paper gap, there is such a necessity that an eccentricity amount of the carriage guide shaft is enlarged (which leads up to increase of a shaft diameter of the carriage guide shaft), or a rotation angle of the carriage guide shaft is enlarged, and there is structural limitation of the carriage guide shaft.
Further in such the paper gap adjusting device, on the occasion that the pair of carriage guide shafts move up and down over rotating in an eccentric manner, a planet gear wheel train, which configures a motive force transmission mechanism between the carriage guide shafts, does not move up and down at the same time, and therefore, by that configuration as it is, there occurs phase lag in planet motion rotation due to a planet gear between the carriage guide shafts. Consequently, on the occasion of configuring the planet gear wheel train, a design in consideration of the above-described rotation phase lag due to a planet motion has been required.
In addition, when an eccentricity amount of the carriage guide shaft is enlarged, the carriage guide shaft moves in not only up and down directions, but also back and forth directions (a paper carrying direction or a sub scanning direction), and therefore, a land-in position of an ink droplet becomes out of alignment, and it becomes impossible to perform high precision recording. In addition, a paper gap relates closely to a rotation angle of the carriage guide shaft, and therefore, in order to ensure high precision position of a paper gap, strict rotation angle control of the carriage guide shaft was required. In addition, each of the above-described two type adjusting devices of a paper gap uses a drive motor for paper feed as a drive source, and therefore, a switching mechanism for a paper gap switching operation or a paper feed operation was required separately.